This invention relates to a field marker for mounting on an agriculture implement to generate a marked line on the ground indicative of the path of the implement.
Field markers are commonly used on farming implements to score a mark outward from one side of an implement when making an operating pass so that the mark may act as a directional guide to the operator on a subsequent pass. Folding field markers are also common so that long arms may be compactly folded inward to the implement for more compact transportation between operating locations.
An example of a folding field marker is shown in U.S. Pat. No. 5,027,525, issuing to Haukass, which shows a bi-fold field marker having a device which automatically folds the outer arm to lie along the inner arm when an actuator acts on the inner arm to fold it inward to the implement on which it is mounted. This particular field marker is also exemplary of the incorporation of a breakaway device which allows the arm to fold rearwardly when it encounters an obstacle. The spring of this breakaway device includes a spring serving two functions, one being to provide resetting force for the break action provided by a cradle, the other being to serve as a down force biasing means. The spring provides bias to relieve some of the weight of the marker arm to vary the downward force with which the end of the marker scores the ground. The spring of the Haukaas patent, depending on soil hardness or other variables, can be difficult to adjust to give the most desirable combination of resetting force and down force. It is known that the design disclosed in the Haukaas patent is often manufactured with a shear pin to retain the marker in the field position and which must be replaced after a breakaway action occurs; otherwise the resetting spring is not able to return and maintain the arm in the operating position.
The Haukaas design has a mount structure with two members connected by a horizontal pivot to allow the outer end of the marker arm vertical movement relative to the implement over uneven ground. An additional member, a cradle, is provided with a vertical joint to allow a breakaway action.
It is an object of this invention to provide a field marker with an automatically re-setting breakaway mechanism.
It is a feature of this invention that the field marker allows for independent setting of breakaway resetting force and down force biasing.
It is still another object of this invention to improve the action of the folding arm in a folding field marker.
It is an advantage of this invention to provide a mounting for a field marker that is manufactured with fewer parts than previously known in the prior art.
A field marker for mounting on an agricultural implement in accordance with one aspect of the invention includes an elongated arm adapted to project outwardly laterally of the implement when in its operating position and being adapted to carry a field marking device at its outer distal end for making a score mark on the ground, a mount for said arm at an inner proximal end thereof allowing pivoting of said arm about first and second generally transverse axes whereby to allow the arm to swing upwardly and downwardly about the first one of said axes when operating on uneven ground while also allowing said arm to swing around the second one of said axes from its outwardly projecting operating position into another position; and a breakaway link pivotally connected to said mount and extending alongside said arm to retain said arm in the operating position but which permits said arm to swing relative to said mount about the second axis away from its outwardly projecting operating position when an obstacle is encountered and a predetermined force on said arm has been exceeded, said breakaway link having a resetting device associated therewith to assist in returning said arm to the operating position once the obstacle has been cleared.
The breakaway link preferably extends in general parallelism to said arm when the latter is in the operating condition.
In one embodiment the breakaway link extends from a pivot point on said mount which is spaced from the second axis to a pivot point associated with said arm, said breakaway link comprising a pair of link members hinged together and adapted to move from (a) a slightly misaligned condition where the breakaway link acts as a rigid link capable of withstanding compressive forces arising from draft forces on said arm during normal operation whereby to inhibit the arm from swinging about the second axis on said mount to (b) a collapsed condition corresponding to a breakaway position of the arm after an obstacle has been encountered.
The above-noted resetting device typically comprises a biasing device which tends to hold the breakaway link members in the slightly misaligned condition until the predetermined force has been exceeded and the collapsed condition of the breakaway link members occurs.
Adjustment means may be provided for varying the degree of misalignment between said breakaway link members whereby to enable the force causing breakaway to be predetermined.
In another embodiment the breakaway link may include a compressible member which compresses when the predetermined force has been exceeded to permit swinging of the arm away from its operating position. The compressible member preferably includes a pair of telescoping members having a compression spring thereon to bias said members in directions away from one another.
The field marker arm typically includes inner and outer arm sections secured together by a folding joint to permit said inner and outer arm sections to be folded and brought into the transport position. An actuator is preferably provided for effecting the folding about said folding joint of said inner and outer arm sections into and out of the transport position, said actuator also holding said inner and outer arm sections in general alignment as the arm is swung away from its operating position when an obstacle is encountered.
The folding joint in one embodiment includes a crank arm and a fold link associated therewith and wherein said breakaway link extends from said pivot point on said mount in spaced generally parallel relation to said inner arm section to a pivot point on said crank arm, with the crank arm and fold link adapted to cooperate with the breakaway link such that as said inner arm section is rotated, said outer arm section rotates relative thereto.
Preferably said actuator is connected between said inner arm section and said crank arm whereby extension and retraction of said actuator effects rotation of the crank arm relative to said inner arm section and at the same time by virtue of the interaction between the linkages defined by said breakaway link, crank arm, mount and inner arm section effects the rotation of the inner arm section relative to said mount.
The field marker preferably includes a biasing device acting between said mount and said arm to apply lifting forces to the arm whereby the field marking device is provided with the required degree of total down force as to enable a suitable score mark to be made.
The preferred embodiment of the present invention has a simplified marker arm mounting structure having only two main members. The marker arm is connected to the second member on a generally vertical axis to allow folding and unfolding of the marker arm. In the present embodiment this same vertical axis also provides for the breakaway action. The second member is attached to a first member directly on a horizontal axis. This allows the second member to pivot about the first member, and allows the outer end of the marker arm vertical movement when operating over uneven ground. In the transport position the vertical axis is held generally vertical or slightly inclined inwardly. In the operating position, the vertical axis is slightly inclined outwardly.
A field marker for mounting on an agricultural implement in accordance with another aspect of the invention includes an elongated arm adapted to project outwardly laterally of the implement when in its operating position and being adapted to carry a field marking device at its outer distal end for making a score mark on the ground, a mount for said arm at an inner proximal end thereof allowing pivoting of said arm about first and second generally transverse axes whereby to allow the arm to swing upwardly and downwardly about the first one of said axes when operating on uneven ground while also allowing said arm to swing around the second one of said axes from its outwardly projecting operating position into a transport position; said arm including inner and outer arm sections secured together by a folding joint to permit said inner and outer arm sections to be folded into juxtaposition with one another and brought into the transport position, an actuator mounted to said inner arm section for effecting rotation of said inner and outer arm sections, and a mechanism interacting between said mount and said inner and outer arm sections and connected to said actuator such that as said inner arm section is pivoted by said actuator through a selected angle relative to said mount, said outer arm section is pivoted about said foldingjoint through an angle relative to said inner arm section substantially greater than the extent of said selected angle.
The above-noted mechanism in a preferred form of the invention is adapted to effect pivoting of said outer arm section through an angle approximately twice the extent of the angle through which said inner arm section pivots.
The mechanism noted above preferably includes an elongated link extending generally parallel to said inner arm section from said mount, and a crank arm pivotally connected between distal end portions of the inner arm section and said elongated link, said crank arm being linked to said outer arm section, and said actuator being connected such that as it extends and retracts said crank arm is rotated and said inner and outer arm sections are caused to pivot relative to one another.
These and other objects, features and advantages can be accomplished according to the instant invention by providing a field marker for mounting on an agricultural implement, the field marker including an elongated arm adapted to project outwardly laterally of the implement when in its operating position and being adapted to carry a field marking device at its outer distal end for making a score mark on the ground. A mount for the arm at an inner proximal end thereof allows pivoting of the arm about first and second transverse axes whereby to allow the arm to swing upwardly and downwardly about the first one of said axes when operating on uneven ground while also allowing the arm to swing around the second one of said axes from its outwardly projecting operating position into another position. The arm includes inner and outer arm sections secured together by a folding joint to permit the inner and outer arm sections to be folded into juxtaposition with one another and brought into the transport position. An extensible actuator effects relative rotation of the inner and outer arm sections, and a mechanism interacts with the inner and outer arm sections and the actuator such that as the inner arm section is pivoted through a selected angle, the outer arm section is pivoted about said folding joint relative to the inner arm section. A breakaway link on the arm permits the arm to swing as a whole relative to the mount about the second axis away from its outwardly projecting operating position when an obstacle is encountered and a predetermined force on said arm has been exceeded. The breakaway link has a resetting device associated therewith for returning the arm to the operating position once the obstacle has been cleared.